Aircraft mechanics Ira McFadden (left) of the 548th Propulsion Maintenance Squadron and Mike Blackmore of the 76th Propulsion Maintenance Group torque the diffuser on an F119 jet engine at Tinker AFB on August 23rd, 2013. The diffuser is where the jet fuel is atomized,or reduced to a fine spray. [USAF photo by Mike Ray]

Twin F119 turbofan jet engines propel the F-22 Raptor, and the these engines are scheduled for programmed depot maintenance upon reaching 4,325 total accumulated cycles, said Brian Thompson, F119 program manager.

A cycle spans the period from when the throttle is shifted from down to full military power and back down again, and Raptor engines have begun reaching the cycle threshold, he said.

Programmed depot maintenance takes 13 to 14 months to complete, which includes a total teardown of the modules and their various components.

"We are ramping up repairs of the F119 modules, and more parts will be routed to the component repair cells," Thompson said.

The Oklahoma City Air Logistics Complex received two of the engines this year and expects two more before the year is out, Thompson said.

The F119 workload at the logistics complex is projected to double in the fiscal years ahead; eight engines are projected to be repaired in fiscal year 2014, 16 in 2015 and 32 in 2016, Thompson said.

Currently, there are 23 mechanics working on the engines in the heavy maintenance center, and by 2017, the group will have 75 to 80 mechanics working on F119 engines, Thompson said.

And that count only includes the front shops that disassemble the modules, he added. It does not include scores of mechanics who will be needed in the back shops to repair the various components removed from the modules.

The F119 has five modules -- fan, gearbox, core, low-pressure turbine and nozzle -- that are disassembled and repaired at the logistics complex. The modules, in turn, have 405 components.

Some of the component repair work is also performed by the engine manufacturer, Pratt & Whitney, or by contractors.

The first F119 engine sent to Tinker was completed in December 2012. The F-22 entered service in the Air Force eight years ago.